App Domain

Question

hi all Can any one explain app domain concept mainly I want to know when the App Domain is created by CLR's worker process exe? Thanks Ebi

Vijaya Kadiyala · Answer

Hi An application domain is the CLR equivalent of an operation system's process. An application domain is used to isolate applications from one another. This is the same way an operating system process works. The separation is required so that applications do not affect one another. This separation is achieved by making sure than any given unique virtual address space runs exactly one application and scopes the resources for the process or application domain using that addess space. However a CLR application domain is seperate from a process. It is contained within an operating system process. A single CLR operating system process can contain multiple application domains. There are some major pluses to having application domains within a single process. Check out the below link http://codebetter.com/blogs/raymond.lewallen/archive/2005/04/03/61190.aspx Thanks -- Vj http://dotnetvj.blogspot.com

Niradhip Chakraborty · Answer

Operating systems and runtime environments typically provide some form of isolation between applications. For example Microsoft Windows uses processes to isolate applications. This isolation is necessary to ensure that code running in one application cannot adversely affect other unrelated applications. Application domains provide an isolation boundary for security reliability and versioning and for unloading assemblies. Application domains are typically created by runtime hosts which are responsible for bootstrapping the common language runtime before an application is run. The logical and physical boundary created around every .NET application by the Common Language Runtime (CLR). The CLR can allow multiple .NET applications to be run in a single process by loading them into separate application domains. The CLR isolates each application domain from all other application domains and prevents the configuration security or stability of a running .NET applications from affecting other applications. Objects can only be moved between application domains by the use of remoting. For most applications we do not need to create our own application domain the runtime host (Worker Process) creates necessary application domains .However and sometimes an application program might also want to work with application domains. For example an application program could load an application component into a domain to be able to unload the domain (and the component) without having to stop the entire applications Creating: In the following cases generally we create an application domain 1. If we create our own runtime host application 2. If our application needs to create or work with additional application domains that are not automatically generated by the runtime. 3. If the requirement is such that some assemblies have to be managed personally If this is the case we create our own application domain load the assemblies that are supposed to be managed personally into application Domain. AppDomain Class has CreateDomain() method //To create an app Domain Explicitly AppDomain.CreateDomain(AppDomainName); Console.WriteLine(app.FriendlyName);// Displays child domain name Console.WriteLine(AppDomain.CurrentDomain.FriendlyName); // Displays Host Domain name Unloading : When you call a Web service by using SSL and an application domain must be unloaded If the call is in progress the application domain does not unload a System.CannotUnloadAppDomainException exception is thrown and the Microsoft ASP.NET worker process may die. So when we make a call to web service using SSL we explicitly unload the application domain programmatically by AppDomain.Unload method Note : An application domain may be unloaded for some reason that is unrelated to calling the Web service. For example if the Web.config file is modified the application domain may be unloaded Please follow the links below http://www.gotdotnet.com/team/clr/AppdomainFAQ.aspx http://www.webopedia.com/TERM/A/application_domain.html